Three-dimensional antenna array system

Abstract

A three-dimensional (3D) antenna array system in the form of a phased array antenna with a first antenna array and a second antenna array, a calibration circuit with an external signal generator, and a hinged power transformer is described. The external signal generator is electrically connected to the first antenna array, and the first antenna array is electrically coupled to the second antenna array via the hinged power transformer. The hinged power transformer mechanically connects the first antenna array to the second antenna array in a first and a second position, with the first antenna array being positioned at an angle to the second antenna array when the hinged power transformer is in the first position.

Description

IntroductionIn-vehicle radar systems may be used to detect and locate other vehicles, pedestrians, and fixed or moving objects when installed in ground vehicles.Antenna arrays used in various applications such as radar, experimental data acquisition, etc. must operate coherently in time, frequency and phase. Due to changing conditions (such as ambient temperature, humidity, aging of the components, etc.), periodic calibration of time, gain, and phase of the transmit / receive chains of the system arrangement is required.Accurate calibration of phase, gain, frequency and related parameters is essential for applying group processing algorithms for estimating radar parameters such as direction of arrival, time delay, Doppler shift, etc. Known methods for calibrating an antenna array require a special design, which may involve separating the antennas or otherwise engaging the antennas to introduce a calibration signal. Additionally, automotive radar systems may be calibrated only once during vehicle production. However, during normal system operation, radar systems installed at different locations of a vehicle may be exposed to different ambient temperatures. For example, one portion of the radar system may face the sun while another portion is in the shadow, thereby creating a temperature differential. In such cases, temperature-related phase differences may become noticeable and affect the overall performance of the radar.In some cases, antenna arrays have three-dimensional (3D) shapes to improve their spatial resolution in azimuth, elevation, or both. An antenna with a 3D group consists of multiple antenna boards, with one board or assembly rotated at an angle with respect to a motherboard. Such arrangements may present a particular electromechanical challenge in their calibration when the calibration signal needs to be directed to an adjacent antenna array (e.g., printed circuit board) that is disposed at an angle to a motherboard.DESCRIPTION OF THE INVENTIONThe concepts described herein provide a three-dimensional (3D) antenna array for a vehicle having a foldable configuration that enables and facilitates phase and gain calibration in real-time. The real-time phase and gain calibration is performed to account for changes in parameters that may occur due to aging and / or real-time environmental variations.An aspect of the disclosure may include a three-dimensional (3D) antenna array system in the form of a phased array antenna having a first antenna array and a second antenna array, a calibration circuit having an external signal generator, and a hinged power transformer. The calibration circuit is electrically connected to the first antenna group, and the first antenna group is electrically coupled to the second antenna group via the foldable power transformer. The foldable power transformer mechanically connects the first antenna group to the second antenna group in a first position and a second position, respectively, wherein the first antenna group is arranged at an angle with respect to the second antenna group when the foldable power transformer is in the first position.Another aspect of the disclosure may include the first antenna group being disposed in a horizontal plane and the second antenna group being disposed in a vertical plane when the foldable power transformer is in the first position.Another aspect of the disclosure may include the hinged power transformer electrically coupling the first antenna group to the second antenna group when the hinged power transformer is disposed in the first position.Another aspect of the disclosure may include the external signal generator generating a pilot signal, the pilot signal being routed to the first antenna group, and the hinged power transformer routing the pilot signal to the second antenna group when the hinged power transformer is disposed in the first position.Another aspect of the disclosure may include that the pilot signal is a short-term radio frequency (RF) signal having a continuous sine wave.Another aspect of the disclosure may include the foldable power transformer having a primary winding, a secondary winding, and a ferrite core.Another aspect of the disclosure may include the ferrite core having a first end and a second end while the first end is hinged to the second end.Another aspect of the disclosure may include the primary winding being disposed at the first end of the ferrite core and the secondary winding being disposed at the second end of the ferrite core.Another aspect of the disclosure may include the foldable power transformer including a primary winding and a secondary winding, wherein the primary winding and the secondary winding are arranged in parallel and spirally wound around a common core member.Another aspect of the disclosure may include that the hinged power transformer includes a non-ferrite core.Another aspect of the disclosure may be that the primary winding is arranged to rotate on the common core member with respect to the secondary winding.Another aspect of the disclosure may include that the foldable power transformer includes a plurality of primary windings having a first number of turns and a plurality of secondary windings having a second number of turns.Another aspect of the disclosure may include that the first number of turns is equal to the second number of turns.Another aspect of the disclosure may include the calibration circuit having a first power divider coupled to the first antenna group via a first directional coupler and a second power divider coupled to the second antenna group via a second directional coupler.Another aspect of the disclosure may include a controller communicating with the calibration circuit and the external signal generator, wherein the controller is configured to feed a pilot signal to the first antenna group and the second antenna group via the external signal generator and the calibration circuit.Another aspect of the disclosure may include an antenna array system including a phased array antenna having a first antenna array and a second antenna array, a calibration circuit having an external signal generator, a hinge, and a hinged power transformer; wherein the hinge mechanically connects the first antenna array to the second antenna array in a first position or a second position, respectively; wherein the first antenna array is disposed at an angle with respect to the second antenna array when the hinged power transformer is disposed in the first position; wherein the calibration circuit is electrically connected to the first antenna array; and wherein the first antenna array is electrically coupled to the second antenna array via the hinged power transformer.Another aspect of the disclosure may include an antenna array system including a phased array antenna having a first antenna array and a second antenna array, a calibration circuit having an external signal generator, a hinge, and a hinged power transformer. The hinge mechanically connects the first antenna array to the second antenna array in a first position and a second position, respectively. The first antenna group is arranged in a horizontal plane, and the second antenna group is arranged in a vertical plane when it is in the first position, and is arranged in a horizontal plane when it is in the second position. The external signal generator of the calibration circuit is directly electrically connected to the first antenna group and electrically coupled to the second antenna group via the hinged power transformer.A system and method are described that enable dynamic in situ calibration of a radar system to accurately estimate radar parameters such as heading, time delay, Doppler shift, etc. without disconnecting the antennas or making other interventions.The above features and advantages, as well as other features and advantages of the present teachings, will be readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the present teachings as defined in the appended claims, taken in conjunction with the accompanying drawings.Brief Description of the DrawingsOne or more embodiments will now be described by way of example with reference to the accompanying drawings, in which: FIG. 1 schematically illustrates a vehicle with a radar system including a 3D antenna assembly according to the disclosure. FIG. 2 schematically illustrates an embodiment of a 3D antenna assembly including a first antenna group, a second antenna group, and a hinged power transformer as described in the disclosure. FIG. 3 schematically illustrates an embodiment of a 3D antenna assembly including a first antenna group, a second antenna group, a hinged power transformer, and a calibration circuit, in accordance with the disclosure.FIGS. 4 and 5 schematically show embodiments of a hinged power transformer that may be used in an embodiment of the 3D antenna assembly in accordance with the disclosure.The drawings are not necessarily to scale, presenting a somewhat simplified representation of various features of the present disclosure as disclosed herein, including, for example, particular dimensions, orientations, locations, and shapes. Details associated with such features will be determined in part by the particular intended application and use environment.Detailed DescriptionThe components of the embodiments described and illustrated herein may be arranged and configured in a variety of different configurations. Therefore, the following detailed description is not intended to limit the scope of the claimed disclosure, but is merely representative of possible embodiments thereof. Moreover, while numerous specific details are set forth in the following description to provide a thorough understanding of the embodiments disclosed herein, some embodiments may be practiced without some of these details. In addition, for clarity, detailed description of certain technical details known in the art have been omitted so as not to unnecessarily obscure the disclosure. For convenience and clarity only, directional terms such as top, bottom, left, right, top, over, above, below, below, behind, and front are used in the drawings. These and similar directional terms are not to be construed as limiting the scope of the disclosure. Moreover, the disclosure as illustrated and described herein may be practiced without an element not specifically disclosed herein.Referring now to the drawings, wherein like reference numerals correspond to like or similar components, FIGS. 1-5, in accordance with the embodiments disclosed herein, schematically illustrate elements of a vehicle 10 having a radar system 20 that includes a three-dimensional (3D) antenna assembly 30 having a first antenna group 40 and a second antenna group 50 that are mechanically connected and electrically connected using a hinged power transformer 60. A dynamic calibration circuit 70 with an external signal generator 71 is arranged to interact with the 3D antenna assembly 30 to dynamically calibrate the first antenna array 40 and the second antenna array 50 in operation. The vehicle 10 may include, but is not limited to, a ground vehicle in the form of a commercial vehicle, an industrial vehicle, an agricultural vehicle, a passenger car, an aircraft, a watercraft, a train, a sport utility vehicle, a passenger transport device, a robot, and the like, to accomplish the purposes of this disclosure. The vehicle 10 advantageously includes a powertrain 12, a telematics system 14, and a navigation system 16, and may also include an advanced driving assistance system (ADAS) 18 that provides some level of autonomous vehicle control.The 3D antenna assembly 30, in one embodiment, includes the first antenna array 40 disposed at an angle relative to the second antenna array 50 when used. The external signal generator 71 is used to generate and direct a radio frequency (RF) pilot signal that is used by the dynamic calibration circuit 70 to dynamically calibrate the first and second antenna arrays 40, 50 of the 3D antenna assembly 30 in operation. The folding power transformer 60 may be implemented with metal coils that may form a hinge that facilitates folding the 3D antenna assembly 30 to reduce its profile under certain conditions, e.g., when entering a parking facility. The concepts described herein facilitate a calibration process that includes periodic and / or periodic calibration of the phase and gain parameters without having to shut off group reception for calibration. The calibration process involves feeding the RF pilot signal to all reception paths that must behave coherently with respect to time, phase, etc.The radar system 20 provides information about the location and trajectory of vehicles, pedestrians, and other objects in the vicinity of the vehicle 10, which information is passed to the ADAS 18 to allow it to use, e.g., to inform the driver and autonomously control the vehicle 10.The ADAS 18, in one embodiment, includes an on-board control system capable of providing some level of driving automation. The "operator" is the person responsible for operating the vehicle 10 regardless of whether it is actively involved in controlling one or more vehicle functions or controls autonomous vehicle operation. Driving automation may include various dynamic driving and vehicle functions. Driving automation may include some level of automatic control or intervention related to a single vehicle function, such as steering, accelerating, and / or braking, where the operator is constantly constantly monitoring the vehicle 10. Driving automation may include some level of automatic control or intervention related to simultaneous control of multiple vehicle functions, such as steering, accelerating, and / or braking, with the operator constantly having overall control over the vehicle. Driving automation may include simultaneously automatically controlling vehicle functions including steering, accelerating, and braking, with the driver providing control over the vehicle 10 for a period of time during the trip. Driving automation may include simultaneously automatically controlling the driving functions of the vehicle, including steering, accelerating, and braking, with the operator providing control over the vehicle for an entire trip. Driving automation includes hardware and controllers configured to monitor the spatial environment in different driving modes to perform different driving tasks during dynamic operation. Driving automation may include, as non-limiting examples, cruise control, adaptive cruise control, lane change warning, intervention and control, automatic parking, acceleration, braking, and the like. The ADAS 18 includes one or more vehicle systems and associated controllers that provide a degree of driving automation. The vehicle systems, subsystems, and controllers associated with the ADAS 18 are implemented to perform one or more operations associated with autonomous vehicle functions, including, by way of non-limiting examples, an adaptive cruise control (ACC), a lane guidance and lane keeping operation, a lane changing operation, a steering assist operation, an object avoidance operation, a parking assist operation, a vehicle braking operation, a vehicle speed and acceleration operation, a vehicle lateral movement operation, e.g., as part of the lane guidance, lane keeping, and lane changing operations, etc.Telematics system 14 is a communication system capable of communicating outside the vehicle to communicate with a communication network system having wireless and wired communication capabilities. The communication outside the vehicle comprises the short-range communication from vehicle to vehicle (V2V) and / or the communication from vehicle to everything (V2x). This may include communication with infrastructure monitoring, e.g., a traffic camera, and communication with a pedestrian nearby, etc. Alternatively or additionally, telematics system 14 may be capable of establishing short-range wireless communication with a handheld device, e.g., a mobile phone, a satellite phone, or other telecommunication device. In one embodiment, the handheld device is loaded with a software application that includes a wireless protocol for communication with telematics system 14, and the handheld device performs off-board communication for communication with an on-board controller via a communication network, which may be in the form of a satellite, cellular antenna, and / or other communication mode. Telematics system 14 may also include a global position system (GPS) sensor that may be used by navigation system 16.The on-board radar system 20 may be configured as a multiple input / multiple output (MIMO) system including the 3D antenna assembly 30.The 3D antenna assembly 30 is arranged as a phased array antenna comprising a first antenna array 40 and a second antenna array 50 mechanically interconnected and electrically connected to a hinged power transformer 60. The external signal generator 71 of the calibration circuit 70 is coupled to the first antenna group 40. The 3D antenna assembly 30 includes a transmitter group, a receiver group, a dynamic calibration circuit 70, and a signal construction controller 80. The elements of the on-board radar system 20 may be configured to operate as a non-linear frequency-modulated (NLFM) system in one embodiment. The transmit frequency and associated operating parameters for the NLFM system are selected to achieve the desired range, range resolution, angular resolution, and speed resolution values for the expected operating environment of the vehicle 10. The NLFM system is designed to generate and transmit tansec waveforms that resolve the skew error of the beam by compensating for the additional phase variation of the skew error.In one embodiment, the first antenna array 40 is disposed in a horizontal position in the vehicle and the second antenna array 50 may be disposed in either a horizontal position (when stowed) or a vertical position (when active).The folding power transformer 60 facilitates the mechanical folding of the second antenna array 50 and also allows the real-time calibration of the phase and gain parameters of each path via the calibration circuit 70 on-line without requiring that the array receive be disabled for calibration.The 3D antenna assembly 30 includes one or more assemblies rotated at an angle to each other. The folding power transformer 60 is used to route the RF pilot signal from the calibration circuit 70 to adjacent packages and boards. The hinged power transformer 60 may be implemented with metal coils forming a hinge with which the 3D antenna assembly 30 may be folded as needed.FIG. 2 schematically illustrates an embodiment of the 3D antenna assembly 30, including the first antenna group 40, the second antenna group 50, the folding power transformer 60, and the external signal generator 71 of the calibration circuit 70.The first antenna group 40 includes a first plurality of antennas 42 a, 42 b,... 42m, which are arranged in a nominal horizontal plane and are all electrically connected to the calibration circuit 70.The second antenna group 50 includes a second plurality of antennas 52 a, 52 b,... 52n which are disposed in a nominal vertical plane and are all electrically connected to the external signal generator 71 via the foldable power transformer 60.FIG. 3 schematically shows further details of an embodiment of the 3D antenna assembly 30, including the first antenna group 40, the second antenna group 50, the folding power transformer 60, and the calibration circuit 70.The first antenna group 40 includes the first plurality of antennas 42 a,... 42m, where "m" represents the numerical number of the first plurality of antennas 42. The first plurality of antennas 42 a,... 42m are all electrically connected to the calibration circuit 70. The calibration circuit 70 includes a 1-bis(m+1) power divider 72 connected to the external signal generator 71, a plurality of directional couplers 76 a,..., 76 m, and a plurality of receivers 77 a,..., 77 m, all of which are connected to a signal construction control unit 80. The directional couplers 76a,... 76m are each embodied as first and second transmission members that are arranged in parallel and are close enough together so that energy passing through one is injected into the other. When used in this manner, directional couplers 76a,... feed. 76m simultaneously insert the RF pilot signal into the signals transmitted from the antennas 42a,... 42 mand detected by the plurality of receivers 77 a,... 77m.The second antenna group 50 includes the second plurality of antennas 52 a,... 52n, where "n" represents the numerical number of the second plurality of antennas 52. The second plurality of antennas 52 a,... 52n are all electrically connected to calibration circuit 70. The calibration circuit 70 includes a 1-bis(n) power divider 74, a plurality of directional couplers 75a,..., 75n, and a plurality of receivers 73a,.... 73n, all of which are in communication with the signal construction control unit 80. The directional couplers 75 a,... 75 nare each embodied as first and second transmission elements which are arranged in parallel and are arranged so close to one another that energy passing through one is coupled into the other. When used in this manner, directional couplers 75a,...75n concurrently feed the RF pilot signal into the signals detected by antennas 52a,...52n and processed by the plurality of receivers 73a,...73n.The external signal generator 71 generates and forwards the RF pilot signal to the 1-to-(m+1) power divider 72. The 1-to-(m+1) power divider 72 divides the RF pilot signal into m+1 signals that are applied to the first plurality of antennas 42 a,... 42m of the first antenna group 40 and also generates a second electric power signal which is transmitted to the 1-bis(n) power divider 74 via the foldable power transformer 60 and a phase control circuit 90. The 1-to-(n) power divider 74 divides the second electric power signal into n signals that are applied to the second plurality of antennas 52 a,... 52 nof the second antenna group 50.In some cases, the calibration signal (local oscillator / LO signal) split between the first and second power dividers 72, 74 is too weak to be received by the second power divider 74 due to various design constraints. In such cases, the signal may need to be amplified. An amplifier introduces an unknown phase shift. The phase locked loop 90 includes a selectable phase locked loop to account for the unknown phase shift during the calibration process.FIG. 4 schematically illustrates an embodiment of the folding power transformer 60 that may be used in an embodiment of the 3D antenna assembly 30 described herein. The foldable power transformer 60 includes a divided ferrite core 61 having a first end 62 and a second end 63, the first and second ferrite ends 62, 63 being connected by hinges 64 and locking mechanisms 65. Primary windings 66 consisting of Np turns and originating from the calibration circuit 70 and the first antenna group 40 are shown at the first end 62 of the split ferrite core 61, and secondary windings 67 consisting of Ns turns and coupled to the second antenna group 50 are shown at the second end 63 of the ferrite core 61.FIG. 5 schematically illustrates an embodiment of the folding power transformer 560 that may be used in an embodiment of the 3D antenna assembly 30 described with reference to FIG. 2. The foldable power transformer 560 is arranged with primary windings 561 and secondary windings 562, the primary windings 561 and the secondary windings 562 being arranged in parallel and spirally wound around a common core element 563. The common core member 563 may be cylindrically shaped and is arranged to act as a hinge 564. In one embodiment, the common core member 563 is made of a ferritic material, e.g., steel. In one embodiment, the common core member 563 is made of a non-ferritic material, e.g., a polymer. In one embodiment, the primary windings 561 are embodied as Np turns and the secondary windings 562 as Ns turns. In one embodiment, the Np turns of the primary windings 561 are equivalent to the Ns turns of the second windings 562.A radar calibration process includes one or more algorithms executed in or by the signal designer controller 80 to control elements of the calibration circuit 70 and the radar system 20 to dynamically calibrate the radar system 20 during its ongoing operation. The radar calibration process includes generating the RF pilot signal via the external signal generator 71 and directing the RF pilot signal to the first plurality of antennas 42 a,... 42m and the second plurality of antennas 52a,..., 52n during a portion of the idle periods. The RF pilot signal is simultaneously fed into all reception channels 77, 73 of the antenna groups 40, 50 using the first and second power splitters 72, 74. The injection of the RF pilot signal into each of the channels is via directional couplers 76, 75. the RF pilot signal may experience different delays and attenuations in the receive channels of the antenna array due to imbalance in the circuit of the receive channels that may be caused by manufacturing variations, aging, temperature, etc. When the RF pilot signal is a continuous sine wave (CW), a delay difference between channels shorter than one cycle of the RF pilot signal is exhibited as a phase offset and a variation of signal gain. The phase offset may be estimated with respect to a reference channel that is one of the reception channels. The calibration process includes introducing gain and phase offset adjustments to each of the receive channels to eliminate the effects of delays and attenuations between the channels, thereby enabling coherent signal reception in a signal build controller of the on-board radar system 20 that relates to the location and trajectory of vehicles, pedestrians, and other objects proximate the vehicle 10.The term "controller" and related terms such as control module, module, controller, controller, processor, and similar terms refer to one or various combinations of application specific integrated circuits (ASICs), electronic circuits, central processing units, e.g., microprocessors and associated non-transitory memory components in the form of memory and storage devices (read-only memory, programmable read-only memory, random access memory, hard disk drive, etc.). The non-transitory memory component is capable of storing machine readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuits, input / output circuits and devices, signal conditioning and buffer circuits, and other components that can be accessed by one or more processors to provide the described functionality. The input / output circuits and devices include analog-to-digital converters and related devices that monitor inputs from sensors, such inputs being monitored at a preset sampling frequency or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms, and similar terms refer to controller-executable instruction sets including calibrations and look-up tables. Each controller executes control routine(s) to provide the desired functions. The routines may be executed at regular intervals, e.g., every 100 microseconds during ongoing operation. Alternatively, the routines may be executed in response to a triggering event. Communication between controllers and communication between controllers, actuators, and / or sensors may be via a direct wired point-to-point connection, a networked communication bus connection, a wireless connection, or another suitable communication connection. Communication involves the exchange of data signals in a suitable form, e.g. electrical signals via a conductive medium, electromagnetic signals via air, optical signals via optical waveguides and the like. The data signals may be discrete, analog or digitized analog signals representing inputs from sensors, actuator commands, and communication between controllers. The term "signal" refers to a physically perceptible indicator that transmits information, and may be a suitable waveform (e.g., electrical, optical, magnetic, mechanical, or electromagnetic), such as direct current, alternating current, sine waves, triangular waves, square waves, vibrations, and the like, that may propagate through a medium.The teachings may be described herein in terms of functional and / or logical block components and / or various processing steps. Such block components may consist of hardware, software and / or firmware components configured to perform the specified functions. Embodiments in accordance with the present disclosure may be embodied as an apparatus, method, or computer program product. Accordingly, the present disclosure may take the form of a pure hardware variant, a pure software variant (including firmware, resident software, microcode, etc.), or a variant that combines software and hardware aspects and is generally referred to herein as a "module" or "system.". Moreover, the present disclosure may take the form of a computer program product embodied in a tangible medium of expression that embodies computer usable program code.The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments for carrying out the present teachings are defined in the appended claims.

Claims

An antenna array system comprising: a phased array antenna having a first antenna array and a second antenna array, a calibration circuit, and a hinged power transformer; wherein the calibration circuit is electrically connected to the first antenna array; wherein the first antenna array is electrically coupled to the second antenna array via the hinged power transformer; wherein the hinged power transformer mechanically connects the first antenna array to the second antenna array in a first position and a second position, respectively; and wherein the first antenna array is disposed at an angle with respect to the second antenna array when the hinged power transformer is in the first position.The antenna array system of claim 1, wherein the first antenna array is disposed in a horizontal plane and the second antenna array is disposed in a vertical plane when the foldable power transformer is disposed in the first position.The antenna array system of claim 1, wherein the hinged power transformer electrically couples the first antenna array to the second antenna array when the hinged power transformer is disposed in the first position.The antenna array system of claim 3 : wherein an external signal generator generates a pilot signal; wherein the pilot signal is supplied to the first antenna array; and wherein the hinged power transformer forwards the pilot signal to the second antenna array when the hinged power transformer is disposed in the first position.The antenna array system of claim 4, wherein the pilot signal comprises a short-term radio frequency (RF) pilot signal having a continuous sine wave.The antenna array system of claim 1, wherein the hinged power transformer comprises a primary winding, a secondary winding, and a ferrite core.The antenna array system of claim 6, wherein the ferrite core has a first end and a second end, while the first end is coupled to the second end via a hinge.The antenna array system of claim 7, wherein the primary winding is disposed at the first end of the ferrite core and the secondary winding is disposed at the second end of the ferrite core.The antenna array system of claim 1, wherein the foldable power transformer comprises a primary winding and a secondary winding, wherein the primary winding and the secondary winding are arranged in parallel and spirally wound around a common core element.The antenna array system of claim 9, wherein the hinged power transformer includes a non-ferrite core.

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